I can't believe this was so hype it got an anime. They really fumbled this shit man. The only way I can see it is he straight up hated doing it to end it that quick and that flat. This is up there with Toradora! in terms of fumbles.
I think him saying "I introduce my fiance" isn't him proposing off screen, it's him saying "I love her, she's going to be my wife.'
I'd say this is a good step seeing as how she wants to change herself up and doesn't want to rely on him etc. However, with how close this is cutting to the end of...